Adaptive stiffness estimation impedance control for achieving sustained contact in aerial manipulation

This paper presents a manipulator-equipped unmanned aerial vehicle (UAV) performing contact-based surface inspection. Using stereo camera information, a contact point is determined and an approach path is generated to ensure an autonomous workflow. The proposed inspection method uses an impedance controller to regulate the force applied by the end-effector to the contact surface. Due to the often adverse conditions in the real world, the aerial manipulator may fail to achieve contact after approaching the surface. Therefore, the impedance controller is coupled with an online stiffness estimation algorithm to increase the overall robustness of the inspection system and achieve stable surface contact. Finally, simulations in the Gazebo environment and experiments in the real world are performed to show the feasibility of this approach.